Means for continually and simultaneously surveying and aligning railroad track



Nov. 19, 1968 STEWART ET AL 3,411,455

MEANS FOR CONTINUALLY AND SIMULTANEOUSLY SURVEYING AND ALIGNING RAILROADTRACK Filed July 12, I965 6 Sheets-Sheet 1 I [I I INVENTORS JOHN K.STEWART HELMUTH R.E.VON BECKMANN ATTORNEYS.

Nov. 19, 1968 J. K. STEWART ET AL MEANS FOR CONTINUALLY ANDSIMULTANEOUSLY Filed July 12, 1965 6 Sheets-Sheet 2 C/ECMAE CWRVE' saw//v sp/mz 0W I mow/v) q wzwg f INVENTORS F2914. JOHN K. STEWART HELMUTHR. E. VON BECKMANN BY W5 ATTORNEYS.

NOV. 19, 1968 j RT ET AL 3,411,455

MEANS FOR CONTINUAIJLY AND SIMULTANEOUSLY SURVEYING AND ALIGNINGRAILROAD TRACK Filed July l2, 1965 6 Sheets-Sheet 5 l I I I 1 L. i l l 15/ P/MSE 3 RA SENSITIVE R5 R2 AM LIFIER R 0 O 1 503mm? A3 5 INVENTORSJOHN K. STEWART HELMUTH R. E. VON BECKMANN BY W ATTORNEYS.

J. K. STEWART ET AL 3,411,455 MEANS FOR CONTINUALLY AND SIMULTANEOUSLY'SURVEYING AND ALIGNING RAILROAD TRACK Nov. 19, 1968 6 Sheets-Sheet 4.

Filed July 12, 1965 INVENTORS JOHN K. STEWART HELMUTH R.E. VON BECKMANNATTORNEYS.

NOV. 19, 1968 J STEWART ET AL 3,411,455

- MEANS FOR CONTINUALLY AND SIMULTANEOUSLY SURVEYING AND ALIGNINGRAILROAD TRACK Filed July 12, 1965 6 Sheets-Sheet 5 INVENTORS JOHN K.STEWART HELMUTH R.E.VON BECKMANN ATTORNEYS.

Nov. 19, 1968 j STEWART ET AL MEANS FOR CONTINUALLY AND SIMULTANEOUSLYSURVEYING AND ALIGNING RAILROAD TRACK AlQd July 12 1965 6 Sheets-Sheet 6wmw N? $56 mmqhG QQTA NVENTORS JOHN STEWART HELMUTH R.E. VON BECKMANNBYM v W ATTORNEYS.

United States Patent Office 3,411,455 Patented Nov. 19, 1968 3,411 455MEANS FOR CONTINUA LLY AND SIMULTANE- OUSLY SURVEYING AND ALIGNING RAIL-ROAD TRACK John Kenneth Stewart, Dorval, and Helmuth Rolf Erich vonBeckmann, Chateauguay, Quebec, Canada, assigngrs, by mesne assignments,to Tamper Inc, Columbia, .C.

Filed July 12, 1965, Ser. No. 471,285 Claims priority, applicationCanada, July 21, 1964, 907,729; Mar. 20, 1965, 926,145 20 Claims. (Cl.1047) ABSTRACT OF THE DISCLOSURE Apparatus for aligning curves andspirals in railroad track by means of an infra-red reference lineestablishing system comprising a transmitter, a receiver and a shadowboard therebetween and a detection system which compares the trackcondition to the established reference line, which detection systempreferably utilizes the same transmitter as the reference lineestablishing system and comprises a second infra-red beam receiver and asecond shadow board (the second beam receiver may physically be the sameas the first receiver but operate in a separate mode thereto) and atrack aligning jack which is commanded by the receiver of the detectionsystem to throw the track to correct errors in the track as referencedto the reference line system and detected by the detection system.

The present invention relates to means for continually andsimultaneously surveying and aligning railroad track. The invention isparticularly concerned with surveying and aligning railroad track bymeans of a high frequency beam such as for an example an infra red beam.

In our co-pending Canadian application No. 860,141 there is describedmeans for aligning a railroad track in combination with an infra redsurveying device which infra red surveying device comprises a forwardprojector mounted on a rail-engaging buggy, a rearwardly located infrared receiver and a shadow element between the receiver and transmitter.In one specific embodiment of our prior application, there is describedthe use of two receivers with a single infra red' transmitter, which tworeceivers co-operate with a pair of shadow boards in order to indicatewhether the track is out of alignment to the left or to the right of adesired position.

The device according to our prior proposals and the prior art generally,all suffer from the disadvantages that whilst they worked well ontangent track, they became impossible to operate in spiral curveswithout the assistance of an outside surveyor who would first survey thespiral track to be aligned so that the devices of the prior art wouldhave a man-made reference line to which to work.

Of course many of the prior art devices required the assitance of asurveyor for working on tangent track and they could not operatecontinually to simultaneously survey and align the track.

It is an object of the present invention to provide a device suitablefor aligning railroad track in tangent, spiral or curved conditionswhich does not require a surveying run through the spiral or curve priorto lining.

It is a further object of the present invention to provide a devicewhich surveys and aligns railroad track substantially simultaneously byalternate operations.

According to the present invention apparatus for continually surveyingand aligning railroad track comprises a reference line establishingsystem including high frequency beam transmitting means, at least onereceiver element spaced therefrom, and at least one shadow elementtherebetween, the transmitting means and each element being mounted formovement along the track; a detection system comprising a high frequencybeam receiving member and a shadow member spaced therefrom, each memberbeing mounted for movement along the track on the reference line andadapted to co-operate to detect the track alignment condition relativeto the reference line; and track aligning jack means operable inresponse to command signals from the receiving member to correct thetrack alignment.

In one embodiment of the invention the receiver element and the shadowelement are continually driven in a direction transversely of the trackat speeds which are a predetermined function of each other inalternating opposite directions, sensibly determined by beam receptionby the receiver element; whereby to continually hunt about the referenceline.

In one construction, the receiver element and the receiver member arearranged vertically one above the other on a common mount and the shadowelement and the shadow member are correspondingly vertically staggered.According to the feature of the invention, the shadow member and shadowelement, the receiver element and the receiver member and thetransmitting means are all mounted on rail engaging carriages so thatthey may be selectively located on one side of the track or the other.

According to an alternative embodiment of the present invention, thereis provided apparatus for continually and alternatingly surveying andaligning railroad track which comprises a reference line establishingsystem including high frequency beam transmitter means, a receiverelement spaced therefrom, a shadow element therebetween, the transmittermeans and each element being mounted on wheeled carriages for movementalong the track, motor means for moving the shadow element transverselyof the track, motor means for moving the receiver element transverselyof the track, means for determining the transverse displacement ofshadow element, means for determining the transverse'displacement of thereceiver element and means for comparing the displacements whilst theapparatus is moving through spiral track and providing a command signalfor the said motor means whereby to produce a pre-programmedrelationship between the displacements; a detection system comprising ahigh frequency beam receiving member and a shadow member spacedtherefrom, each member being mounted for movement along the track on thereference line established by the pre-programmed receiver and shadowelement, and adapted to co-operate to detect the track alignmentcondition relative to the reference line; and track aligning jack meansoperable in response to command signals from the receiving member tocorrect the track alignment.

The following is a description by Way of example of certain embodimentsof the present invention, reference being had to the accompanyingdrawings in which:

FIGURE 1 is a schematic plan view of an apparatus according to thepresent invention arranged on a railroad track;

FIGURE 2 is a part elevation showing the vertical location of thereceivers, shadow units and transmittter;

FIGURE 3 is a diagrammatic view indicating the position of the differentunits of the system on a curved track;

FIGURE 4 is a graph of empirically derived curves showing the relativemovement of the units of the system during operation;

FIGURE 5 is a circuit diagram used in one embodiment of the inventionand schematically shows a bridge circuit for comparing the displacementsof the different elements of the system and for applying apre-programmed relationship to the displacements of the units;

FIGURE 6 is a schematic illustration of an infinitely variable gearoperable together with the circuit of FIG- URE 5 to produce thepre-programmed relationship of the displacements of the elements of thereference line establishing system throughout any spiral curve; and

FIGURE 7 is a detail of an alternative embodiment of the invention;

FIGURE -8 is a diagrammatic representation of a drive for the receiversaccording to that alternative embodiment;

FIGURE 9 is a diagram to which reference is had in a computation made inthe description, and

FIGURE 10 is a view similar to FIGURE 3 but of a further alternativeembodiment of the invention in somewhat more elaborate apparatus thanthe other two embodiments.

Turning now to the drawings. A high frequency beam transmitter, in theform of at least one infra red light transmitter 10, is mounted on aself-propelled leading satellite car 11. An infra red beam receiverelement 14 and an infra red beam receiver member 15 are mounted oneabove the other (for the sake of ilustration, they are shown one infront of the other in FIGURE 1 but their actual position is as shown inFIGURE 2) on a trailing satellite car 19. The car 19 is connected to andtowed by a self-propelled aligning carriage 20 beneath which is mounteda double acting hydraulic jack 21. On the end of the rams 22 of the jack21 are rail engaging clamp members 23, which engage the grade rail 24and the other rail 25 to throw the track to the left or to the right. Ashadow member 26 is floatingly mounted on and extends to one side of thecar 20 and is biased from the rail 25 of the track and urged in thedirection of the grade rail 24. Shadow element 28 is mounted on anintermediate carriage 30 which is con nected to and pushed by theself-propelled carriage 20.

It will of course be understood, that one receiver alone could beutilized as long as a suitable switching arrangement is provided to letthe receiver function alternately as the receiver element of thereference line establishing system and as the receiver member of thedetection system. If one receiver alone is used a suitable means forretracting the shadow element and the shadow member will need to beprovided and synchronized with the aforementioned switching arrangementsince shadow element 28 and shadow member 26 will need to be physicallypositioned in line with each other.

Each of the cars 11, 30 and 19 is spring biased from the rail 25 of thetrack and urged in the direction of the grade rail 24 for referencepurposes.

The self-propelled leading car 11 normally proceeds the intermediate car30, the carriage 20 and the car 19 by a considerable distance (of theorder of 50 to 100 feet) and the intermediate car 30, the carriage 20and the rear car 19 are suitably stationed by means connecting links 33,34.

Shadow element 28 on the intermediate car 30 is mounted so that it canbe arranged selectively on either side of the car 30 and is mounted sothat it, the shadow element, can be driven backwards and forwards in thetransverse direction as indicated by the arrow by a stepping motor 37.The shadow member 26 on the aligning carriage 20 is arranged to extend apredetermined distance D (the same as the spacing of the transmitter 10)outside the selected one of the rails 24 or 25. The double actinghydraulic jack 21 may, for example, operate in conjunction withexternally located ballast engaging jacks and 41 which are used to liftthe track by applying a lifting action through clamping member 23.

The receiver element and the receiver member are mounted on a commonmount on the car 19 so that they may be driven backwards and forwards ina transverse direction as seen by arrow 35 by a stepping motor 36.

In order to be able to continually and alternatingly survey and correcttracks, applicant uses the transmitter 10, the shadow element 28 and thereceiver 14 to establish a reference line and uses the receiving member15 and the shadow member 26 as a detection system to detect the trackcondition relative to the reference line, command signals beingtransmitted from the receiving member 15 to jack 21 to correct the trackalignment.

In operation on tangent track the front car 11 precedes the vehicles 30,20 and 19 and projects an infra red cone of light adjacent the graderail 24. The shadow element 28 moves forwards and backwards as indicatedby the arrow 35 in response to the drive motor 37 which drives theshadow element in one direction and then in other, the sense of thedirection of drive being determined by whether or not the receivingelement 14 sees the transmitted beam. The receiving element 14 and theshadow element 28, which is driven in one direction and then the otherby motor 37 at the same speed but in opposite directional phase to thereceiver element 14; hunt about a central station and thereby establisha reference line with the transmitter 10. That is to say, the shadowelement 28 is driven towards the top of the sheet as viewed in FIGURE 1,into the projected beam and the receiving element 14 is driven towardsthe bottom of the sheet as viewed in FIG- URE 1 across the centre of theprojected beam from the transmitter 10 until the shadow element 28obscures the receiving element 14 from the transmitted beam from thetransmitter 10. As soon as the receiving element 14 ceases to receivethe transmitted beam, it by means of any suitable photo-electric device,causes the motors 36 and 37 to be reversed to that the shadow element 28is now driven towards the bottom of the sheet as viewed in FIGURE 1 andthe receiving element is driven towards the top of the sheet as viewedin FIGURE 1 until the light path between the transmitter 10 and thereceiver 14 is again open. As soon as the receiving element 14 receivesthe transmitted beam, it again causes the reversal of the motors 36 and37 so that in this fashion the receiving element 14 and the shadowelement 28 are caused to continually hunt about the reference line L. Inpractice, where alignment is conducted on a tie to tie basis one huntingoperation per tie would probably suffice to establish the referenceline. That is to say the receiver and shadow elements are intermittentlydriven in transverse direction.

While the appartus is operating on tangent track the shadow element 28and the receiver 14 hunt about a reference line which is spaced by adistance D from the grade rail 24, however when the apparatus has tonegotiate curved track, the receiver element and the shadow element 28have to take up appropriate positions to establish a reference line aswill be seen from FIGURES 3, 4 and 9.

The distance E is the distance of the receiver element 14 from its datumor zero position and the distance F is the distance of the shadowelement 28 from its datum or Zero position. The ratio E/F is the ratioused to establish the reference line and it varies through a variety ofvalues through spiral curves and is a constant in tangent and circularcurved track.

In a circular curved track the constant value E/F is determined from thefollowing equations which hold good for the nature and magnitude ofcurves F 01 cos Simplify:

Further simplify:

E/ F 1.28 for the values A= ft. B= ft. C= ft.

While entering into a spiral, that is from the time the transmitter 10enters the spiral until the shadow element 28 enters the spiral, theratio E/F is proportional to the distance A and the distance B (bysimilar triangles) and for the values given is constant at 20/25=0.8=E/F.

However, from the time the shadow element enters the spiral unit thereceiver 14 enters the curved track the ratio E/F varies constantly. Byplotting a spiral curve from civil engineering tables and plotting thevalues E and F against the percentage of spiral, the graphs of E and Fand thus the ratio E/ F as seen in FIGURE 4, was derived. The infinitelyvariable cone gear drive illustrated in FIG- URE 6 is designed togetherwith the electrical bridge network of FIGURE 5 to satisfy the conditionsexisting through the spiral by pre-progralmming the related movements ofthe shadow element 28 and the receiver 14 to provide the correct E/Fratio. That is to say, the drive of FIGURE 6 and the electrical bridgenetwork provide an electrical simulation of the graph of the ratio E/ FThis is achieved by using the bridge circuit of FIGURE 5 to compare theratio of the actual instantaneous displacement of the shadow elementfrom its datum and that of the receiver 14 from its datum, with the E/Fratio required to form the reference line and to generate a commandsignal which is superimposed on a normal hunting cycle of the shadowelement 28 and the receiver 14 whereby to cause these members toreposition themselves if the required E/F ratio does not exist, untilthe bridge is in balance and the required E/F exists.

Thus with E/F representing the required geometrical ratio and e/frepresenting the actual ratio of the instantaneous actual displacementpositions of the shadow element 28 and receiver 14 from their datumpositions, as applied to the bridge network in electrical analogue formby the transducers 50, connected to the shadow element 28, and 51connected to the receiver element 14, then (referring to FIGURE 5),

RQ/RP=E/F (required) and R2/R4=e/f (actual) to prove that RQ/RP=R2/R4for balance:

R3 +RD=RK Condition for balance:

RS/R2=RK/R4 RQ- R2 RP R4 R2 R4 R4(RQ--R2) =R2 (RP-R4) R4RQ-R4R2=R2RPR2R4R4RQ=R2RP RQ/RP=R2/R4 E/ F =e/ f The required E/F ratio called for bythe bridge is dependent upon the positions of the wipers of thepotentiometers 55 .and 56 which are driven from the wheel of the rearcar through an infinitely variable cone gear drive as illustrated inFIGURE 6. It will be clear from the graphs of E and F and of the ratioE/F, and whilst the nature of the curves is true for all spirals, sincethe graphs are plotted against the percentage of spiral, which is alength, it is necessary that the wipers of the potentiometers 55 and 56have completed their travel when the apparatus For balance on the trackhas passed through the spiral, in other words that of the spiral length(no matter what it measures in actual distance) corresponds to the fulltravel of the wipers. This control is achieved by means of the geardrive of FIGURE 6 by ensuring that a gear ratio is selected in which .aninput, via rail engaging wheel 46, of 100% of spiral distance willresult in an output drive from the gears sufiicient to move the wipersof the potentiometers through their full distance. Mechanically this isobtained by connecting the wheel 46 of the rear car 19 by a chain driveto the input sprocket 60 of the cone gear assembly. The sprocket 60drives a shaft 61, and through clutches indicated .at 63 and 63A,through a selected one of a pair of gear paths, the input drive cone 65.The two gear paths are necessary, as it becomes apparent later, since asthe vehicles proceed through an ingoing spiral to a circular curve, therotation of the wheel 46 is in the same direction as when the vehiclesleave the circular curve through an exit spiral curve, although for thepurpose of this apparatus it is required to drive the potentiometers 55and 56 in the opposite sense while exiting. Thus by utilizing the firstgear path indicated at 67 the cone gear 65 is driven in a clockwisedirection, whilst by using the other gear path 68, which includes anidler 69, the cone 65 is driven in an anti-clockwise direction. Theoperator of the vehicle by positioning an idler friction wheel betweenthe drive cone 65 and the driven cone 71 to a precalibrated position tocorrespond to the length of the spiral and indicated by the marker 73,ensures that the output from the cone 71 on the output shaft 75 whichdrives the wipers of the potentiometers 55 and 56, is such that when thewheel 46 has passed through the full length of the spiral, the output onshaft 75 will have been geared to drive the wipers of the potentiometers55 and 56 from position 1 to position 2 in an ingoing spiral and fromposition 2 to position 1 for an exit spiral of the same length.

In operation when the device enters a spiral transitional curve betweentangent track and circular track the front car 14 will of course be intothe spiral curve whilst the vehicles 30, 20 and 19 are still on tangenttrack and the condition E/F=0.8 will pertain. On entering the spiral theoperator will have selected the necessary switches to switch theresistances RE and RD out of the balancing circuit and since RA and RBwill have been selected such that the bridge calls for an E/F=0.8, this0.8 value is then electrically superimposed on the hunting circuit insuch a fashion that the motor 37 becomes retarded in a directiondetermined by the sign of the imbalance. This causes the covereddisplacement of the receiver 14 to be 0.8 of the covered displacement ofthe shadow element 28 so that the receiver 14 is driven from its datumposition until it establishes a new reference line. Thereafter thenormal hunting of shadow element 28 and receiver 14 recommences aroundthe newly established reference line. This condition exists until shadowelement 28 enters into the spiral at which point the condition E/F=O.8ceases to apply.

Since the distance between transmitter 10 and shadow element 28 isknown, a suitable drive (not shown) may be connected to the wheel 46 assoon as transmitter 10 enters into the spiral so that the wheel 46measures the distance travelled by the cars and operates to switch inresistances RE and RD into the bridge and to operate the clutch 63A tobring the infinitely variable cone drive (FIGURE 6) into drivingconnection with the wheel 46 (gear path 67 being selected as it is aningoing spiral). During the passage through the spiral from the pointwhere the condition E/F=0.8 ceases to exist until the circular curve isreached where the condition E/F=1.28 exists, the displacement of theshadow element 28 from its datum position F to the displacement of thereceiver element 14 from its datum position B will vary in accordancewith the curves of the graphs as seen in FIGURE 4. As the shadow element28 enters the spiral curve, that is the point where the ratio E/F=0.8ceases to exist, and resistances RE and RD are switched into the bridge,the drive from the wheel 46 positions the wipers of the potentiometers55 and 56 in accordance with the requirements to electrically simulatethe graph of E/F and this unbalances the bridge and must be compensatedfor by alteration of both RA and RB. The required E/ F is constantlycompared in the bridge with the analogue of the instantaneous actualdisplacement from zero position of the element 28 and receiver 14, thatis the actual E/F, and depending upon the sign of the inbalance, theshadow element 28 is retarded in the required direction causing thereceiver not to see the transmitted beam or to see it for too long thuscausing the motor 36 to reposition the receiver 14 to provide therequired E/F ratio, thereby establishing the new reference line. Thereceiver element 14 and the shadow element 28 continue to hunt about thechanging reference line throughout the spiral. When the device entersthe circular curve a suitable switching arrangement is actuated todisconnect clutch 63A and thus the drive from the wheel 46. At thispoint the wipers of the otentiometers will have been driven to theirposition 2 and the bridge will now require an E/F=1.28 to be satisfiedand a new reference line has to be established. This condition persiststhroughout the circular track.

As the device starts to leave the circular curve and enter the exitspiral, the operator operates switching which energizes the clutch 63 tocause the wheel 46 to drive, this time through gear path '68, the conegear in the direction opposite to that for the ingoing spiral. In orderto take into account the very large upswing in the ratio E/F as thevehicles approach the end of the exit spiral and re-enter tangent track,the valve of RQ in the bridge has to be increased relative to RP, oralternatively RP has to be decreased relative to RQ to provide thenecessary E/F for values from 1.28 to a value approaching infinity.Since the vehicle has entered the circular curve via an ingoing spiralthe wipers of the potentiometers 55 and 56 are at their position 2. Onentering the exit spiral the drive shaft 75 from the cone gear drives 56from the position 2 to position 1 but the potentiometer 55 is switchedopen from the bridge and a fixed resistance (not shown) equal to themaximum value of 55 is switched into the bridge circuit to take itsplace. Therefore, when 56 reaches position 1 equal to zero resistance,maximum value for RQ/RP, approaching infinity, is obtained.

The detection system comprising the shadow member 26 and the receivingmember 15, indicates when the track at the working station, where theshadow member 26 is located, is out of alignment with reference to thereference line L, since the shadow member 26 and the receiver member areright on the reference line L. That is to say, if the receiver member 15does not see the projected infra red beam from the projector 10, itsignals the jack 21, in conventional fashion, to, operate solenoidvalves to throw the track to the right and the throwing continues untilthe track (and the shadow member 26 biased against it) is'movedsufficiently far to let the receiver member 15 see the transmitted beanwhereupon the jack is stopped instantly. If, on the other hand thereceiver member 15 sees the transmitted beam, it signals to the jack 21to throw the track to the left until the shadow member 26 obscures thetransmitted beam, whereupon the jacking to the left ceases.

In practice a reference line establishing operation is performed andthis is immediately followed by an aligning operation, the operationbeing conducted alternately to form a series of working cycles. The timedifference is, however so small, that the apparatus can be said tosimultaneously survey and align the track.

Obviously the receivers 14 and 15, the shadow member 26 and thetransmitter 10 are selectively moved to either side of their cars whenthe shadow element is moved to accommodate a right hand or left handcurve.

A second embodiment of the invention is best seen 8 from FIGURES 1, 2, 7and 8, this embodiment is suitable for use on tracks, such as forexample low speed tracks, where the accuracy of lining obtained with theforegoing more sophisticated embodiment is not required. The transmittercar 11 and its infra red light transmitter 10, the intermediate car 30and its shadow element 28, the jacking and aligning car 20 with itsshadow member 26, and the rear satellite car with the receivers 14 and15, are all basically the same as before, however the receivers 14 and15 and thin mount 16 are now arranged on a platform 18 (indicated indotted lines in FIGURE 1) on the rear satellite car 19.

The platform 18 (best seen in FIGURE 7) may be mounted on either side ofthe rear satellite car 19. The mount 16 on which the receivers 14 and 15are located is arranged centrally on a transversely extending screw jackdevice 42 (FIGURE 7). The mount 16 and jack 42 are in turn mounted in aquadrant 43. The mount 16 and the receivers 14 and 15 are driventransversely on the screw jack 42 by means of a stepping motor 36similar to the motor 36 of the previous embodiment but, which drives ata speed 1.28 times the speed of the motor 37. The screw jack 42 isarranged for pivotal movement on the quadrant 43 around its pivot point45 by means of a drive best seen in FIGURE 8. As will be seen in FIGURE8, one of the wheels 46 and the rear buggy 19 is connected with a gearbox through a chain reduction 151. The gear box, through a worm drive152, drives an elliptical wheel 154 on an ellipse drive 154, 155, 156.The ellipse drive 154, 155, 156 comprises a pair of identical ellipticalwheels 154, mounted to rotate on different axes and connected by anelastic connection 156. The elliptical wheel 55 drives the screw jack 42through a gear drive 158. The drive 158 drives a drum 159, and through asteel cable wound thereon, and connected at both ends to anchoringpoints on the quadrant 43, pivots the quadrant 43 about the pivot point45 and therefore swings the screw jack 42 along the curved path as indicated by the arrow 63 in FIGURE 7 whilst the receivers 14 and 15 ontheir mount 16 are driven along the screw jack 42. The receiver 15 thentraces out a path as indicated by the ghost representations in FIGURE 7and is maintained facing the front by means of a pantograph 62 whichpivots the receivers 14 and 15 in their mount 16.

As with the previous embodiment in order to be able to continuallysurvey and correct tracks, applicant uses the transmitter 10, the shadowelement 28 and the receiver 14 to establish a reference line and usesthe receiving member 15 and the shadow member 26 as a detection systemto detect the track condition relative to the reference line, commandsignals being transmitted from the receiving member to jack 21 tocorrect the track alignment. The drive illustrated in FIGURES 7 and 8 ismade to satisfy the conditions, explained mathematically above, existingthrough the spiral.

As before the front buggy 11 proceeds the train of bug ies 30, 20 and 19and projects an infra red cone of light adjacent the grade rail. Theshadow element 28 moves forward and backward as indicated by the arrow35 in response to the drive motor 37 which drives the shadow element 28at constant speed first in one direction and then in the other, thesense of the direction of drive being determined by whether or not thereceiving element 14 sees the transmitted beam. The receiving element 14and the shadow element 28 hunt about a central station and therebyestablish a reference line with the transmitter 10. That is to say, theshadow element 28 is driven upwardly (as viewed in FIGURE 1) into theprojected beam and the receiving element 14 is driven downwardly (asviewed in FIGURE 1) across the centre of the projected beam from thetransmitter 10 until the shadow element 28 obscures the receivingelement 14 from the transmitted beam from the transmitter 10. As soon asthe receiving element ceases to receive the transmitted beam, it, bymeans of any suitable photo-electric device, causes the motor 36 and 37to be reversed so that the shadow element 28 is now driven downwardly(as viewed in FIGURE 1) and the receiving element is driven upwardly (asviewed in FIGURE 1) until the light path between the transmitter 10 andthe receiver 14 is again open. As soon as the receiving element 14receives the transmitted beam, it again reverses the motors 36 and 37 sothat in this fashion the receiving element 14 and the shadow element 28are caused to continually hunt about the reference line L. Again, wherealignment is conducted on a tie to tie basis one hunting operation pertie would probably sufiice to establish the reference line. That is tosay the receiver and shadow elements are intermittently driven intransverse direction. It will be seen that as the device enters aleft-handed spiral curve, the front buggy 14 will of course be into thespiral curve whilst the train 30, and 19 is still on tangent track andthe condition E/F=0.8 will pertain. While this condition exists thereceiver will be in the starting position as seen in FIGURE 7 and willbe driven inwardly and hunt along the screw jack 42. Although the motor36A drives at a speed 1.28 times the speed of the motor 37, because ofthe inclination of the screw jack 42 the resulting speed normal to thetrack is reduced and is in fact 0.8 times the speed of the shadowelement 28. Continuing the progress, intermediate buggy is next into thespiral curve (which ceases the conditions E/F=0.8) then the jacking car20, and finally the rear buggy 19. During the passage through the spiralfrom the point where the condition E/F=0.8 ceases to exist until thecircular curve is reached where the condition E/F=1.28 exists, thedistance of the shadow element 28 from its datum position F to thedistance of the receiving element 14 from its datum position B will varyin accordance with the curves of the graphs seen in FIGURE 4. Now sincethe shadow element 28 is driven at a constant speed by the motor 37 andsince the motor 37 drives in step with the motors 36A which drives thereceiver 14 backwards and forwards along the screw jacks 42, variationsof E to F must be compensated for by an increase or decrease of therelative speed of movement of the receiving element 14 to the shadowelement 28 and this, as has been indicated hereinbefore is accomplishedby means of the drive in FIGURE 8. The operator is aware of the lengthof the spiral before the circular curve section is reached and by theexpedient of selecting the appropriate gear in the gear box 50 tocorrespond to length of the spiral curve, the wheel 46, through thearrangement indicated in FIGURE 8, drives the quadrant 43 rearwardly topivot the screw jack 42 and the receiver 14 thereon about its pivotpoint 45 to provide the correct speed ratios to correspond to the valuesof E and F taken from the graphs of FIGURE 4.

With the receiver element 14 and the shadow element 28 hunting at theappropriate speed ratios about the reference line L, the reference lineis maintained throughout the spiral.

The quadrant 43 continues to swing until the wheel 46 has made thenecessary number of revolutions to drive it, through the selectedgearing 50 against the back stop 44. A switch (not shown) disconnectsthe drive from the wheel 46 and now since the apparatus is in curvedtrack the speed of the motor 36 is the appropriate 1.28 times the speedof the motor 37.

By reversal of the proceedings when coming out of the curve a roughapproximation to the variations when leaving the curve is achieved.

Again, the detection system comprising the shadow member 26 and thereceiving member 15, indicates When the track at the working station,where the shadow member 26 is located, is out of alignment withreference to the reference line L, since the shadow member 26 and thereceiver member 15 are right on the reference line L. That is to say, ifthe receiver member 15 does not see the projected infra red beam fromthe projector 10, it signals the jack 21, in conventional fashion, tothrow the track to the right and the throwing continues until the track(and the shadow member 26 biased against it) is moved sufiicient- 1y farto let the receiver member 15 see the transmitted beam whereupon thejack is stopped instantly. If, on the other hand the receiver membersees the transmitted beam, it throws the track to the left until theshadow member 26 obscures the transmitted beam, whereupon the jacking tothe left ceases.

FIGURE 10 shows a somewhat more elaborate reference line establishingsystem of a third embodiment of the invention, in which two shadowelements 28A and 28B are used together with two receiving elements 14Aand 14B and at least one projector 10. The appropriate transverse speedsfor the ratio E /F and E /F are derived as before, by plotting fromcivil engineering tables and during hunting are used to locate areceiving member 15. Again the receiving elements 14A and 14B may bemounted vertically above one another together with the receiving member15.

Now if 28A is of equal length to 28B and is located geometrically at anequal distance from 10 as 28B is from 26, 28A will furnish one of threepieces of information while 28B and 14B are hunting:

(1) When interception of reference line L coincides with length of 28B,the curve being lined is circular, length of 28A or 28B being indicativeof degree of curvature.

(2) When 28A overshoots reference line L, the curve is a spiral withincreasing degree of curvature, the amount of overshoot beingproportional to a required correction for this particular spiral atreceivers 14A and 14B.

(3) When 28A is missing the reference line L, the reverse of thecondition in sub-paragraph 2 above applies. This provides immediateinformation that the curve is a spiral with decreasing degree ofcurvature and the amount of undershoot is indicative of rate of changeof curva ture.

This instantaneous information permits automatic identification of thenature of the curve.

It will be seen also that instead of making the shadow member 26 fixedand locating the receiving member 15 the roles could be reversed and thereceiving member 15 fixed with the shadow board being located on thereference line L.

What we claim as our invention is:

1. Apparatus for aligning railroad track comprising a reference lineestablishing system including a high frequency beam transmittingelement, at least one beam receiver element spaced from the transmitterelement by a predetermined distance, and at least one shadow elementlocated at a predetermined position therebetween, means to impart apredetermined relationship to the positional displacements of theelements transversely of the track whereby to establish a reference linetherewith, the elements being mounted for movement, in station, alongthe track; a track condition detection system comprising a beamreceiving member mounted for movement along the track and beingoperatively located in predetermined relationship to said receiverelement; a shadow member located at a predetermined poistion between thetransmitter and the beam receiving member and adapted to co-operate withthe beam receiving member to sense the track alignment conditionrelative to the reference line; and track aligning jack means operablein response to command signals from the receiving member to correct thetrack alignment.

2. Apparatus as claimed in claim 1 in which the means to impart thepredetermined relationship to the positional displacements of theelements comprises means to drive the receiver element and the shadowelement in alternatin g opposite directions.

3. Apparatus as claimed in claim 2 wherein the predeterminedrelationship is established by driving the receiver and shadow elementsat predetermined speed ratios.

4. Apparatus as claimed in claim 1, in which the receiver element andthe receiving member are arranged vertically one above the other on acommon mount and in which the shadow element and the shadow member arecorrespondingly vertically staggered.

5. Apparatus as claimed in claim 1 in which the shadow member, theshadow element, the receiver element and the receiving member and thetransmitting element are all mounted on rail engaging carriagesselectively on one side of the track or the other.

6. Apparatus as claimed in claim 1 in which the transmitting element ismounted on a self-propelled lead bugg the receiver element on a rearbuggy, and the shadow element on an intermediate buggy; and in which thereceiving member is mounted for movement with the receiver element andthe shadow member is located at a work station on a jacking car.

7. Apparatus as claimed in claim 1 wherein a plurality of receiverelements and a plurality of shadow elements are provided for thereference line establishing system.

8. Apparatus as claimed in claim 7 in which the receiver elements andshadow elements are associated in pairs and are continually driven, inorder to impart the predetermined relationship to the said positionaldisplacements, in a direction transversely of the track, the speeds ofeach pair of elements being a predetermined function of each other inalternating opposite directions sensibly determined by beam reception bythe receiver element of the pair.

9. Apparatus as claimed in claim 7 in which the receiver elements arearranged vertically one above the other on a common mount and, to impartthe predetermined relationship to the said positional displacements, arecontinually or intermittently driven in a direction transversely of thetrack, and in which the plurality of shadow elements are continually orintermittently driven in a direction transversely of the track to impartsaid predetermined relationship, the elements being driven inalternating opposite directions, the speed of the receiver elements andtheir mounts being a predetermined function of the transverse speed ofthe shadow elements, the sense of movement being determined by beamreception by the receiver element.

10. Apparatus as claimed in claim 2 further comprising means fordetermining the transverse displacement of a shadow element from adatum, means for determining the transverse displacement of the receiverelement from a datum and means for examining the displacements whilstthe apparatus is moving through curved track and providing a commandsignal for the driving means whereby to pre-programme the displacementrelationship.

11. Apparatus as claimed in claim 10 in which the means for determiningthe transverse displacement of the shadow element from a datum includesa transducer means for providing an electrical analogue signal of theinstantaneous displacement of the shadow element from its datum; inwhich the means for determining the transverse displacement of thereceiver element from the datum includes transducer means for providingan electrical analogue signal of the instantaneous displacement of thereceiver element from its datum; and in which the means for examiningthe displacements while the apparatus is moving through curved trackincludes means for generating a signal of a required relationshipbetween the displacement of the shadow element and receiver elementagainst which signal the said displacement analogue signals are comparedwhereby to produce the command signal to operate the drive means for thereceiver and shadow elements to produce the required displacementrelationship.

12. Apparatus as claimed in claim 10 in which the means for determiningthe transverse displacement of the receiver element and the means fordetermining the transverse displacement of the shadow element comprisetransducer means adapted to apply an electrical analogue of theinstantaneous displacement of the elements to the means for examiningthe said displacements.

13. Apparatus as claimed in claim 12 in which the means for examiningthe displacements comprises an electrical bridge network.

14. Apparatus as claimed in claim 11 in which the means for generatingthe command signal of the required relationship between thedisplacements of shadow ele ment and receiver element and for comparingthe said analogues therewith comprises an electrical bridge networkincluding potentiometer means controlled in accordance with the distancetravelled by the apparatus through the transitional spiral section ofthe curve.

15. Apparatus as claimed in claim 14 in which the wipers of the saidpotentiometers are connected through an infinitely variable gear with arail engaging wheel.

16. Apparatus as claimed in claim 15 in which the infinitely variablegear is provided with means to select a gear ratio corresponding to thelength of the transitional spiral section of the curve whereby to drivethe potentiometer wipers through their full range of travel for onehundred percent traversal of the transitional spiral section by theapparatus.

17. Apparatus as claimed in claim 16 in which the infinitely variablegear includes two gear paths one for an ingoing spiral transitionalcurve and a second for an exit spiral transitional curve.

18. Apparatus as claimed in claim 16 in which the infinitely variablegear comprises a pair of parallel axes, oppositely directed, cones witha friction idler therebetween to transmit rotation from a driven one ofthe cones to drive the other, and means to position the idler axiallywith respect to the cones, which last mentioned means constitute themeans to select the said gear ratio.

19. Apparatus as claimed in claim 10 in which the receiver element andthe beam receiving member are physically the same receiver and switchingmeans is provided to cause its appropriate function and to snychronizethe selected retraction of either of the shadow element or shadow memberout of the beam to permit the performance of both functions alternately.

20. Apparatus as claimed in claim 10 in which the high frequency beamtransmitter means transmits in the infra red area of the spectrum.

References Cited UNITED STATES PATENTS 3,144,834 10/1964 Stewart 1047ARTHUR L. LA POINT, Primary Examiner.

R. A. BERTSCH, Assistant Examiner.

